The present invention relates to an image receptor surface to be used for image formation through thermal transfer. More particularly, the invention relates to an image receptor surface which offers an interesting aesthetic effect by making an image transferred thereto visible or invisible depending on the temperature thereof, and to a method for making the same.
Various thermal image transfer methods have been conventionally known. One of the thermal image transfer methods heretofore proposed is such that a polyester film carrying an image printed thereon with a sublimation dye recording agent is used as a thermal transfer sheet and the image on the thermal transfer sheet is thermally transferred onto an image receptor surface by heat and pressure. The term xe2x80x9cimage receptor surfacexe2x80x9d is herein meant by a surface or layer of an image receptor to which an image of a sublimation dye recording agent is thermally transferred for formation of the image therein. The image receptor surface is provided on a base to ensure effective thermal image transfer. Therefore, the image receptor surface should have a good dye affinity and dye fixability.
The prior art image receptor surface only serves to fix the dye transferred thereto, but does not offer any aesthetic effects to an article on which the image is formed. In this connection, there has been a demand for a thermal image transfer method which offers aesthetic effects by employing an image receptor surface. Such a demand can be satisfied, for example, by providing an image receptor surface which is adapted to conceal an image (including an illustration and letters) thermally transferred thereto at a temperature out of a predetermined temperature range and turn colorless to make the concealed image visible at a temperature within the predetermined temperature range. More specifically, such an image receptor surface is formed on a surface of a base such as a mug, and an image including unique pictorial and textual messages desired to be sent to a specific person is thermally transferred to the image receptor surface. At this time, the image formed in the image receptor surface is latent but, when the person pours hot water into the mug, the latent image is made visible so that the person receives the unique pictorial and textual messages.
As a result of intensive studies, the inventors of the present invention have found that the aforesaid idea can be realized by employing the following image receptor surface, and attained the present invention. In accordance with the present invention, the image receptor surface receives an image of a sublimation dye thermally transferred thereon from a foundation sheet for formation of the image therein, and comprises a thermochromatic layer.
In accordance with one preferred embodiment of the present invention, the image receptor surface, which is formed on an article, is thermochromatic so that its color changes, for example, when the image receptor surface is heated up to a predetermined temperature range. An image (including an illustration and letters) is thermally transferred to the image receptor surface in a conventional manner. The image thus transferred to the image receptor surface is concealed in an image formation area on the article by the color of the image receptor surface, for example, at ordinary temperature and, when the article is heated, the color of the image receptor surface is changed so that an interesting aesthetic effect is added to the image formation area.
In the invention, a thermochromatic ink may be used for formation of the thermochromatic layer of the image receptor surface. The thermochromatic ink is herein meant by an ink composition which changes its color depending on the temperature thereof. In accordance with one preferred embodiment of the present invention, there is provided an image receptor surface which comprises a thermochromatic layer formed of a thermochromatic ink.
It is an object of the present invention to provide a unique image receptor surface comprising a thermochromatic layer which has an image concealable color at a temperature out of a predetermined temperature range so that an image thermally transferred thereto is invisible or latent, and becomes colorless or transparent at a temperature within the predetermined temperature range so that the latent image is made visible, and to provide a method of making the same.